It's an antenna & it needs to be a certain length - making it a bit gay just adds enough pizazz (length) and it's the ez thing to do from a designers pov.

Oh, no, the metal ones do in fact use the metal as an antenna?? Can't really tell (but I would guess not).
yt/wyj7r_C51UU&t=115, yt/P5aszRLpa3Y

I though it was like this:

So the pattern of the cut is maybe structural (harder to bend with the plastic inside it bcs it's longer?) or just perhaps a CNC simplification.